FIG. 1 illustrates the conventional method for making a color filter.
Step A of FIG. 1 shows the starting point, a glass substrate 10 on which is formed a layer 12 a black matrix (Cr) material 12. A layer of photoresist 14 is formed on top of the black matrix material 12. In step B, the photoresist 14 is patterned and removed in selected areas (not shown). The black matrix 12 is then etched in the areas which are exposed due to removal of the photoresist. The remainder of the photoresist is then removed. The result is that portions 16 of black matrix material 12 remain on top of the glass substrate 10.
In step C, the portions 16 of matrix material 12 are coated with gelatin material 18 and a layer 20 of photoresist is deposited on top of the gelatin material 18.
The photoresist 20 is then patterned and it is removed above a particular portion 22 of the gelatin 18. The gelatin portion 22 is then dyed with a red pigment. The remainder of the photoresist 20 is then removed. The result is shown in step D.
The steps C and D are repeated to introduce green dye and blue dye into portions 24 and 26 of gelatin material. The results are shown in steps E.
The result of this method is a color filter with different colors at selected locations.
This conventional method has a number of significant shortcomings. First, the conventional method cannot be used at temperatures above about 300.degree. C. The black matrix layer 12 must itself be patterned, thus requiring an additional substrate layer 10 to be used. In addition, the light radiation resistance of the resulting filter is not good.
It is an object of the present invention to provide a method for making a color filter which overcomes the shortcomings of the prior art process. In particular, it is an object of the invention to provide a process for making a color filter which can be carried out at high temperatures, which does not require the additional substrate layer required for such patterning, which has good light radiation resistance, and which has good adhesion.